<!DOCTYPE html>
<html lang="en">

  <head>
    <meta charset="UTF-8">
    <meta name="viewport"
          content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
      @keyframes ColorChange {
        0% {
          outline: 1px solid lightgreen;
        }

        50% {
          outline: 1px solid green;
        }

        100% {
          outline: 1px solid lightgreen;
        }
      }

      svg {
        outline: 1px solid red;
        animation: ColorChange 500ms ease infinite;
      }

      line,
      polyline,
      rect {
        stroke-linecap: round;
        stroke-linejoin: round;
      }
    </style>
  </head>

  <body>
    <svg width="500"
         height="500"
         xmlns="http://www.w3.org/2000/svg"
         xmlns:xlink="http://www.w3.org/1999/xlink"
         preserveAspectRatio="xMinYMin meet"
         viewBox="0 0 500 500">

      <!-- 参考线 -->
      <g style="stroke: gray; stroke-dasharray: 4 4;">
        <line x1="0"
              y1="0"
              x2="200"
              y2="0" />
        <line x1="20"
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              x2="20"
              y2="90" />
        <line x1="120"
              y1="0"
              x2="120"
              y2="90" />
      </g>
      <g transform="translate(20, 0)">
        <g transform="skewX(30)">
          <polyline points="50 0, 0 0, 0 50"
                    style="fill: none; stroke: black; stroke-width: 2;" />
          <text x="0"
                y="60">skewX</text>
        </g>
      </g>
      <g transform="translate(120, 0)">
        <g transform="skewX(30)">
          <polyline points="50 0, 0 0, 0 50"
                    style="fill: none; stroke: black; stroke-width: 2;" />
          <text x="0"
                y="60">skewX</text>
        </g>
      </g>


    </svg>
  </body>

</html>
